1. Field of the Invention
This invention relates to epoxy resin compositions toughened by blending with a modified liquid polysulfide.
Toughened epoxy resin compositions are used in a wide variety of applications, notably in the automotive industry, for forming rigid seals and bonds between components. Such resins offer high resistance to mechanical stresses, even at high temperatures.
2. Description of the Prior Art
One commonly used toughening agent for epoxy resins is carboxyl-terminated butadiene nitrile rubber. This has excellent properties but is expensive and difficult to handle.
Epoxy resins have been modified with liquid polysulfides such as LP-3 and ELP-3 of Morton International Inc. The resulting compositions have however not shown much improvement in peel strength and they have the added disadvantage that the glass transition temperature Tg shows a marked decrease. The compositions thus cannot be used at such high temperatures without changing from a vitreous to a rubbery state with consequent loss of strength.